For a silver halide color reversal light-sensitive material, it is required to apply a very limited and suitable amount of exposure in order to form a useful image, therein because its permissible range of exposure is narrow. This is because the color reversal light-sensitive material is designed so that the gradation is high is compared with a color negative light-sensitive material, since the image formed is used, for example, as a positive image for viewing. Thus it is necessary to use a light-sensitive material having the optimum sensitivity depending on the particular purpose of use and exposing conditions.
Photographing special scenes, such as sports photographs, which require a high shutter speed, and stage photographs, which are obtained under conditions such that the amount of light necessary for exposure is deficient, requires a high sensitivity color light-sensitive material. Only a very limited number of color reversal photographic light-sensitive materials can satisfy the above requirements.
Under such circumstances, it has been desired to develop a high sensitivity color reversal light-sensitive material and a method of controlling sensitivity to compensate for the deficiency of exposure.
In order to meet the above requirements, a number of development accelerating methods and push development methods have been proposed.
A method which has been most popularly employed for a long period of time is to lengthen the time of black-and-white development, or to increase the developing temperature.
This push development method, however, does not always provide a color reversal light-sensitive material with a sufficient sensitization suitability, and causes the following problems:
(1) Sensitization cannot be accomplished unless the time for the first development is greatly increased as compared with the standard processing;
(2) In a light-sensitive material having a structure that comprises a high sensitivity layer and a low sensitivity layer, the sensitizing processing causes changes in gradation because the two layers are different in development processing suitablility;
(3) If the developed film speed is intended to increase by lengthening the time for the first development, a serious decrease in the density of color image occurs; and
(4) The sensitizing treatment causes degradation in the color balance because red-sensitive, green-sensitive, and blue-sensitive layers are different in development processing suitability.
It is known that a development accelerator is used for the purpose of increasing sensitivity. These accelerators are cationic surface active agent, cationic dyes, neutral salts, polyalkylene oxide, organic amines and the like as described in L. F. A. Mason, Photographic Processing Chemistry, pp. 41-44 Focal Press, London and New York (1966). These compounds, however, when added to a black-and-white developer, are not sufficiently high in development accelerating capability, and tend to increase the formation of fog and to decrease the maximum density of a reversal color image. Thus they are difficult to use in a commercial embodiment.
In order to the above problems, a processing method using a black-and-white developer containing a thioether compound is disclosed in Japanese Patent Application (OPI) No. 63530/82 (the term "OPI" as used herein means a "published unexamined Japanese patent application"). This method, however, has a disadvantage in that when the developed film speed is changed by changing the developing time or temperature, each rate of development of the blue-sensitive, green-sensitive and red-sensitive layers is different, and thus the color balance is degraded.
Furthermore, as a method of improving the above disadvantage a processing method using a two bath black-and-white developer is described in Japanese Patent Application (OPI) No. 81644/84. Although this method provides good performance, since the black-and-white development comprises two steps, administration of a processing liquid and processing conditions is complicated and very delicate, and it is difficult to maintain a constant photographic performance.
As an effective method to overcome the above defects in push development, a method for controlling development fog in the black-and-white development is described in L. F. A. Mason, Photographic Processing Chemistry pages 38 and 252 (1966). For example, halogen compounds such as bromides and iodides are well known and widely used in a black-and-white developer. In the case of push development, however, the fog-inhibiting power is not sufficient and the object cannot be attained.
1-Phenyl-5-mercaptotetrazole, 4-phenyl-2-mercaptothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole and 1,2-naphthyl-5-mercaptotetrazole as described in U.S. Pat. No. 2,725,290 possess an effect of inhibiting excessive development of the upper layer of a multi-layer material when the black-and-white development is carried out at high temperatures. These compounds, however, inhibit the development of the upper layer even if used in a small amount because their development-inhibiting effect is very large. Thus if the above compounds are used in an increased amount to prevent the development or fog of the lower layer, they excessively inhibit the development of the upper layer, thereby reducing the color balance.
As compounds having an action which is lower than those of the above development inhibitors or antifoggants, the above-cited reference, L. F. A. Mason, Photographic Processing Chemistry, pp. 39-41, (1966) describes 5-methylbenzotriazole and 6-nitrobenzimidazole. These compounds, however, have disadvantages in that the effect of inhibiting the fog of the lower layer at the black-and-white development is small, and if the amount of the compounds added is increased, sensitivity is decreased because of their strong action inhibiting development of the lower layer.
In the sensitization developing processing or rapid developing processing of a multi-layer color reversal photographic light-sensitive material, it is necessary to balance the fog-preventing effect of each layer at the time of the black-and-white development. It is very difficult to inhibit the formation of fog at the time of black-and-white development while decreasing or eliminating influences on the development of the uppermost layer without decreasing the sensitivity of the lowermost layer.